You ask: "will going veg be enough to produce some noticeable weight loss soon?". The answer is maybe yes and maybe no. You see, it depends on what you eat. The only criteria to be a vegetarian is that you eat no animal flesh - and being one does not necessarily imply a healthy diet. On one hand, there are healthy, trim meateaters who eat an excellent diet (with lots of vegetables, fruits, legumes, whole grains and nuts with a bit of meat on the side), and on the other hand there are fat, unhealthy vegetarians and vegans who eat a terrible diet (lots of sweets, processed foods, fried greasy foods, and very few veggies.)

Like you, I led a pretty decadent life for many years and did not pay much attention to the foods I was putting into my body - and my health suffered as a result (even though I have been a vegetarian for 20 something years, a junk-food-vegetarian). Fortunately, I discovered a book on optimal human nutrition that has changed my life for good. It is called "Eat to Live" by Joel Fuhrman MD. There is an excellent review of Dr Fuhrman's book here at VegSource (this is the article that started me down the road to better eating). Although it is marketed as a lose-weight book (which may appeal to you), it is really a condensed course in modern human nutritional science (forget everything you were taught in school about the food pyramid - much of it is dead wrong). It turns out that the optimal diet for health and longevity consists of lots of vegetables, fruits, legumes, whole grains and nuts, and very little or no processed or animal foods.

The bottom line is that you are on the right track - the best sustainable diet for a trim healthy body excludes all animal foods. And there are other reasons besides health to consider going veg. Another good book to read is "The Food Revolution" by John Robbins. If you're going to read only one book about vegetarianism, this is the one to read.